Deck 6: A Second Look at Classes and Objects

Question 1

Assume the class BankAccount has been created, and the following statement correctly creates an instance of the class: BankAccount account = new BankAccount(5000.0);
What is true about the following statement?
System.out.println(account);

A) A runtime error will occur.
B) The method will display unreadable binary data on the screen.
C) The account object's toString method will be implicitly called.
D) A compiler error will occur.

Answer 1

C

Question 2

Of the following, which would be considered the no-arg constructor for the Rectangle class?

A) public Rectangle(int len, int width)
B) public Rectangle(double len, double width)
C) public Rectangle()
D) All of the above

Answer 2

C

Question 3

If you have defined a class SavingsAccount with a public static method getNumberOfAccounts, and created a SavingsAccount object referenced by the variable account20, which of the following will call the getNumberOfAccounts method?

A) account20.getNumberOfAccounts();
B) SavingsAccount.getNumberOfAccounts();
C) getNumberOfAccounts();
D) None of the above

Answer 3

B

Question 4

Overloading is

A) writing a method that does too much processing.
B) writing a program that is too large to fit in memory.
C) having two or more methods with the same name, but different signatures.
D) having two or more methods with the same signature.

Question 5

When the this variable is used to call a constructor

A) it must be the first statement in the constructor making the call.
B) it can be anywhere in the constructor making the call.
C) it must be the last statement in the constructor making the call.
D) You cannot use the this variable in a constructor call.

Question 6

Assuming the following declaration exists:
Enum Tree { OAK, MAPLE, PINE }
What will the following code display?
System.out.println(Tree.OAK);

A) OAK
B) Tree.OAK
C) 0
D) 1

Question 7

Enumerated types have this method, which returns the position of an enum constant in the declaration list.

A) position
B) location
C) ordinal
D) index

Question 8

The "has a" relationship is sometimes called a(n) ________ because one object is part of a greater whole.

A) enterprise
B) possession
C) mutual relationship
D) whole-part relationship

Question 9

By default, a reference variable that is an instance field is initialized to the value

A) null.
B) 0.
C) void.
D) static.

Question 10

A method's signature consists of

A) the method name and the parameter list.
B) the return type, the method name, and the parameter list.
C) the size of the method in memory.
D) the return type and the method name.

Question 11

When you write an enumerated type declaration, you

A) are actually creating a special kind of class.
B) do not enclose the enum constants in quotation marks.
C) should use the standard convention of writing the enum constants in uppercase.
D) All of the above

Question 12

A class that is defined inside of another class is called a(n)

A) nested class.
B) enumerated class.
C) inner class.
D) helper class.

Question 13

You cannot use the fully-qualified name of an enum constant for

A) a case expression.
B) an argument to a method.
C) a boolean expression.
D) All of the above

Question 14

If the following is from the method section of a UML diagram, which of the following statements is true?
+ equals(object2:Stock) : boolean

A) This is a public method that accepts a Stock object as its argument and returns a boolean value.
B) This is a public method that returns a reference to a String object.
C) This is a private method that receives two objects from the Stock class and returns a boolean value.
D) This is a private method that returns a boolean value.

Question 15

When you make a copy of the aggregate object and of the objects it references,

A) you are performing a shallow copy.
B) you are performing a nested copy.
C) you are performing a deep copy.
D) a compiler error will occur.

Question 16

________ is the term for the relationship created by object aggregation.

A) "Has a"
B) Inner class
C) "Is a"
D) One-to-many

Question 17

If object1 and object2 are objects of the same class, to make object2 a copy of object1

A) write a method for the class that will make a field by field copy of object1 data members into object2 data members.
B) use the copy method that is a part of the Java API.
C) use the default constructor to create object2 with object1 data members.
D) use an assignment statement to make object2 a copy of object1.

Question 18

When a method in the ________ class returns a reference to a field object, it should return a reference to a copy of the field object to prevent "security holes."

A) aggregate
B) inner
C) String
D) nested

Question 19

The only limitation that static methods have is

A) they must be declared outside of the class.
B) they cannot refer to nonstatic members of the class.
C) they can only be called from static members of the class.
D) they can refer to only nonstatic members of the class.

Question 20

When a method's return type is an object, what is actually returned to the calling program?

A) a reference to an object of that class
B) only the values in the object that the method accessed
C) an object of that class
D) a null reference

Question 21

The names of the enum constants in an enumerated data type must be enclosed in quotation marks.

Question 22

CRC stands for

A) Class, Recyclability, Collaborations.
B) Class, Redundancy, Collections.
C) Class, Responsibilities, Collaborations.
D) Code, Reuse, Constancy.

Question 23

Look at the following declaration:
Enum Tree { OAK, MAPLE, PINE }
What is the fully-qualified name of the PINE enum constant?

A) enum.PINE
B) PINE
C) Tree.PINE
D) enum.Tree.PINE

Question 24

If a class has a method named finalize, it is called automatically just before an instance of the class is destroyed by the garbage collector.

Question 25

A declaration for an enumerated type begins with this key word.

A) enumerated
B) enum type
C) ENUM
D) enum

Question 26

What will be returned from the method, if the following is the method header?
Public Rectangle getRectangle()

A) the address of an object of the Rectangle class
B) the values stored in the data members of the Rectangle object
C) a null value
D) an object that is contained in the class Rectangle

Question 27

When an object is passed as an argument, it is actually a reference to the object that is passed.

Question 28

An enumerated data type is actually a special type of class.

Question 29

You may use this to compare two enum data values.

A) the ordinal method
B) the ==, >, and < operators
C) the equals and compareTo methods
D) the moreThan, lessThan, and equalsTo methods

Question 30

enum constants have a toString method.

Question 31

The key word this is the name of a reference variable that an object can use to refer to itself.

Question 32

If you write a toString method for a class, Java will automatically call the method any time you concatenate an object of the class with a string.

Question 33

The JVM periodically performs this process to remove unreferenced objects from memory.

A) memory shuffling
B) system restore
C) garbage collection
D) memory sweeping

Question 34

You can use the enum key word to

A) create your own data type.
B) specify the values that belong to that type.
C) Both A and B
D) Neither A nor B

Question 35

An instance of a class does not have to exist in order for values to be stored in a class's static fields.

Question 36

You can declare an enumerated data type inside of a method.

Question 37

A class's static methods do not operate on the fields that belong to any instance of the class.

Question 38

When a field is declared static, there will be

A) a copy of the field for each method in the class.
B) a copy of the field in each class object.
C) only one copy of the field in memory.
D) two reference copies of the field for each method in the class.

Question 39

A static field is created by placing the key word static

A) after the access specifier and field's data type.
B) after the access specifier and before the field's data type.
C) after the field name.
D) in brackets, before the field's data type.

Question 40

To get the name of a calling enum constant,

A) simply use the enum constant in the statement.
B) use the ordinal method.
C) use the displayName method.
D) use the toString method.